1. Field of the Invention
The present invention relates generally to a touch screen with a soft key and more particularly, to a touch screen with a soft key enabling electromagnetic resonance input.
2. Description of the Related Art
Along with the recent rapid growth of the market for smart phones and touch screens, extensive research has been conducted for these products. A user can input a specific command to a smart phone or other device having a touch screen by selecting a specific position or icon on the display of the smart phone or touch screen with a user's body part or with an ElectroMagnetic Resonance (EMR) pen.
This input scheme can be implemented through a capacitive touch screen. A capacitive touch screen generally includes transparent electrodes and condensers. As the user touches the touch screen with a body part, the touch may be sensed based on the resulting changed capacity of a condenser.
However, since a capacitive touch screen requires a user's touch, this input scheme may be inconvenient for a user and providing accurate input may be difficult. Due to this inconvenience, EMR input has recently become an active study area.
An EMR type input on a touch screen involves controlling generation of electromagnetic waves by applying a voltage to a loop coil disposed on a Printed Circuit Board (PCB) and controlling absorption of the electromagnetic waves into an EMR pen. The EMR pen may include a condenser and a loop and emit the absorbed electromagnetic waves in a specific frequency.
The electromagnetic waves emitted from the EMR pen may be absorbed again into the loop coil of the PCB so that a position near to the EMR pen on the touch screen can be determined based on the absorbed electromagnetic waves.
Meanwhile, a pen may operate in an ElectroMagnetic (EM) fashion as well in the EMR fashion. An EM pen may include a coil for electromagnetic output and an internal power supply for applying a voltage to the coil.
FIGS. 1A, 1B and 1C are conceptual views of a conventional EMR scheme.
FIG. 1A is a diagram illustrating a communication device 100 with an electromagnetic sensing circuit operating in a conventional EMR scheme.
Referring to FIG. 1A, the communication device 100 may include a display 110 and soft keys 120.
The display 110 displays information to a user. The display 110 may operate in an EMR scheme and/or a capacitive scheme.
The soft keys 120 are a user interface provided separately from the display 110, which enables the user to intuitively perform basic functions such as back, cancel, menu display control, etc. Conventionally, the soft keys 120 operate only in the capacitive scheme due to limitations on accommodation of capacitive sensors and electromagnetic sensors under transparent electrodes. Conventional soft keys do not have built-in electromagnetic sensors.
FIG. 1B is a diagram illustrating a plurality of loops arranged in the display of FIG. 1.
Referring to FIG. 1B, a plurality of loops 131 to 134 may be arranged such that the loops overlap with each other. When the user's an EMR pen is moved close to a specific position on the display 110, the loops 131 to 134 may sense an electromagnetic field from the EMR pen.
FIG. 1C is a graph illustrating induced voltage with respect to the loops of the display of FIG. 1B.
Referring to FIG. 1C, each of the loops 131 to 134 may output current induced by the sensed electromagnetic field. A loop closer to the EMR pen will sense an electromagnetic wave with a larger amplitude than loops further away from the EMR pen, and each loop will emit an induced voltage corresponding to the sensed electromagnetic wave. Therefore, induced voltages with different magnitudes may be output as illustrated in FIG. 1C.
A microprocessor built in the communication device 100 may determine a peak by interpolating the magnitudes of the output induced voltages and thus may determine a user-input position on the display.
As stated before, since only the capacitive scheme is used for the soft keys 120, the user must input commands to the soft keys 120 by touching the soft keys 120 with a body part. Moreover, when the user's body part touches a soft key 120, while using an EMR pen, an unintended input such as execution of a back operation through a corresponding soft key may occur. Accordingly, there exists a need for developing a structure for disabling user input via a touch on the soft keys 120, when a user uses an EMR pen.